US20160215830A1 - Friction engagement element - Google Patents
Friction engagement element Download PDFInfo
- Publication number
- US20160215830A1 US20160215830A1 US14/917,490 US201414917490A US2016215830A1 US 20160215830 A1 US20160215830 A1 US 20160215830A1 US 201414917490 A US201414917490 A US 201414917490A US 2016215830 A1 US2016215830 A1 US 2016215830A1
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- Prior art keywords
- friction
- grooves
- oil
- friction plate
- plate
- Prior art date
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- 239000002783 friction material Substances 0.000 claims abstract description 59
- 230000002093 peripheral effect Effects 0.000 claims description 46
- 239000003921 oil Substances 0.000 description 145
- 239000010720 hydraulic oil Substances 0.000 description 44
- 230000005540 biological transmission Effects 0.000 description 35
- 230000007246 mechanism Effects 0.000 description 25
- 239000000314 lubricant Substances 0.000 description 21
- 230000008878 coupling Effects 0.000 description 19
- 238000010168 coupling process Methods 0.000 description 19
- 238000005859 coupling reaction Methods 0.000 description 19
- 230000001050 lubricating effect Effects 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 239000002826 coolant Substances 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D13/00—Friction clutches
- F16D13/58—Details
- F16D13/60—Clutching elements
- F16D13/64—Clutch-plates; Clutch-lamellae
- F16D13/648—Clutch-plates; Clutch-lamellae for clutches with multiple lamellae
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D13/00—Friction clutches
- F16D13/58—Details
- F16D13/74—Features relating to lubrication
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D13/00—Friction clutches
- F16D13/22—Friction clutches with axially-movable clutching members
- F16D13/38—Friction clutches with axially-movable clutching members with flat clutching surfaces, e.g. discs
- F16D13/52—Clutches with multiple lamellae ; Clutches in which three or more axially moveable members are fixed alternately to the shafts to be coupled and are pressed from one side towards an axially-located member
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D13/00—Friction clutches
- F16D13/58—Details
- F16D13/60—Clutching elements
- F16D13/64—Clutch-plates; Clutch-lamellae
- F16D13/68—Attachments of plates or lamellae to their supports
- F16D13/683—Attachments of plates or lamellae to their supports for clutches with multiple lamellae
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D25/00—Fluid-actuated clutches
- F16D25/06—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch
- F16D25/062—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch the clutch having friction surfaces
- F16D25/063—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch the clutch having friction surfaces with clutch members exclusively moving axially
- F16D25/0635—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch the clutch having friction surfaces with clutch members exclusively moving axially with flat friction surfaces, e.g. discs
- F16D25/0638—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch the clutch having friction surfaces with clutch members exclusively moving axially with flat friction surfaces, e.g. discs with more than two discs, e.g. multiple lamellae
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D25/00—Fluid-actuated clutches
- F16D25/12—Details not specific to one of the before-mentioned types
- F16D25/123—Details not specific to one of the before-mentioned types in view of cooling and lubrication
Definitions
- the present disclosure relates to wet friction engagement elements including annular friction plates each having a friction material bonded to its surface and annular separator plates capable of frictionally engaging with the friction plates.
- wet multi-plate clutches including annular friction plates meshing with splines formed in the outer periphery of a hub and each having a friction material bonded thereto and annular separator plates meshing with splines formed in the inner periphery of a drum are known as this type of friction engagement element (see, e.g., Japanese Patent Application Publication No. 2000-145819).
- a plurality of lubricant oil supply holes are formed in the hub.
- a plurality of oil through grooves extending from the inner peripheral edge to the outer peripheral edge of the friction material of the friction plate are formed such that their openings at the inner peripheral edge face lubricant oil supply holes.
- a wet multi-plate clutch which includes a plurality of metal plates fitted in the inner periphery of an input drum and a plurality of facing plates fitted on the outer periphery of an input clutch hub and each having a friction material facing bonded to its both surfaces (see, e.g., Japanese Patent Application Publication No. 2002-106597).
- oil grooves are formed in the surface of each metal plate so as to extend from the inner radial side toward the outer radial side, and clearance extending in the circumferential direction is provided between the inner periphery of the input drum and the outer radial ends of the oil grooves of each metal plate.
- Lubricant oil used to lubricate the metal plates and the facing plates thus flows in the axial direction of the wet multi-plate clutch from each oil groove to the spaces between the input drum and the plurality of metal plates through the clearance, and is discharged to the outside of the input drum through oil discharge openings formed in the input drum.
- a method in which a plurality of segments made of a friction material are bonded at intervals to a core plate having external teeth and a plurality of grooves are formed between the segments is also known as a method for manufacturing a wet friction clutch plate for use in this type of friction engagement element (see, e.g., Japanese Patent Application Publication No. 2004-176915).
- lubricant oil can be discharged from the spaces between each friction plate and each separator plate in a more desirable manner.
- lubricant oil can be discharged from the spaces between each friction plate and each separator plate in a more desirable manner.
- the lubricant oil is not satisfactorily discharged to the outside of the drum and stays inside the drum, a relatively large amount of lubricant oil is present between each friction plate and each separator plate. Accordingly, drag torque due to viscous shear resistance of the lubricant oil may not be satisfactorily reduced when the wet multi-plate clutch is in a disengaged state.
- lubricant oil having flowed in the oil grooves and the clearance can be discharged to the outside of the input drum through the openings formed in the input drum.
- peeling, chipping, etc. of the friction materials may occur as the edges of the oil grooves contact the friction materials of the facing plates when the facing plates frictionally engage with the metal plates.
- the present disclosure according to an exemplary aspect further reduces drag torque that is generated when a friction engagement element is not engaged, while more satisfactorily protecting a friction material bonded to a friction plate.
- a friction engagement element is a wet friction engagement element including a drum having a cylindrical drum portion, a hub having a cylindrical hub portion, an annular friction plate fitted in an inner periphery of the drum portion and having a friction material bonded to its surface, and an annular separator plate fitted on an outer periphery of the hub portion and capable of frictionally engaging with the friction plate, wherein the drum portion has splines on which a plurality of external teeth formed in the friction plate are fitted, and a plurality of through holes formed in grooves of the splines, the friction plate has a plurality of oil grooves formed at intervals in a circumferential direction of the friction plate and extending in a radial direction of the friction plate, and each of the plurality of oil grooves is located next to its adjacent one of the external teeth in the radial direction as viewed in an axial direction of the friction plate.
- the annular friction plate having the friction material bonded to its surface is fitted in the inner periphery of the cylindrical drum portion of the drum, and the annular separator plate capable of frictionally engaging with the friction plate is fitted on the outer periphery of the cylindrical hub portion of the hub.
- the drum portion has the splines on which the plurality of external teeth formed in the friction plate are fitted, and the plurality of through holes formed in the grooves of the splines.
- the friction plate has the plurality of oil grooves formed at intervals in the circumferential direction of the friction plate and extending in the radial direction of the friction plate. Forming the plurality of oil grooves in the friction plate having the friction material bonded thereto can more satisfactorily suppress peeling, chipping, etc.
- each of the plurality of oil grooves is formed next to its adjacent one of the external teeth in the radial direction as viewed in an axial direction of the friction plate.
- Lubricant oil supplied throughout the spaces between the friction material of the friction plate and the separator plate can thus be smoothly guided from each oil groove to the groove of the splines of the drum portion in which the external tooth adjacent to the oil groove is fitted, and can be satisfactorily discharged from each through hole to the outside of the drum portion.
- the lubricant oil can thus be more satisfactorily controlled not to stay inside the drum portion.
- This can more satisfactorily suppress generation of drag torque due to viscous shear resistance of lubricant oil that is present between the friction plate and the separator plate when the friction plate and the separator plate are in a disengaged state.
- the friction material bonded to the friction plate can therefore be more satisfactorily protected, and drag torque that is generated when the friction engagement element is in a disengaged state can further be reduced.
- Each of the plurality of oil grooves may be located next to its adjacent one of the through holes in the radial direction as viewed in the axial direction of the friction plate, and the plurality of through holes may be formed in the drum portion so as to overlap the friction plate as viewed in the radial direction.
- the lubricant oil can thus be more smoothly guided from each oil groove to the through hole adjacent to the oil groove, and the lubricant oil can be more satisfactorily discharged to the outside of the drum portion through each through hole.
- the drum portion may have the splines formed in the inner periphery, the plurality of through holes may be formed such that outside of the drum portion communicates with the grooves of the splines, the friction plate may have the plurality of external teeth that are fitted in the grooves of the splines, and each of the plurality of oil grooves may be formed radially inward of its adjacent one of the external teeth.
- An opening of the oil groove which is located on an inner peripheral side of the friction plate may be formed so as to narrow as closer to an outer peripheral side of the friction plate. This can increase the flow velocity of the lubricant oil flowing in the oil grooves.
- the lubricant oil can thus flow straighter in each oil groove, and the lubricant oil can be more satisfactorily discharged to the outside of the drum portion through the oil grooves and the through holes adjacent to the oil grooves.
- the friction material may have a plurality of non-through grooves each formed between the oil grooves adjoining each other and each opening on the inner peripheral side of the friction plate, and each of the plurality of non-through grooves may be formed next to its adjacent one of the through holes in the radial direction as viewed in the axial direction.
- the friction plate and the separator plate are thus subjected to a force in such a direction that the friction plate and the separator plate are separated from each other due to an oil pressure of the lubricant oil having flowed into the non-through grooves of the friction material. Clearance between the friction plate and the separator plate can thus be more properly maintained, which can further reduce drag torque that is generated between the friction plate and the separator plate.
- each of the non-through grooves is formed next to its adjacent one of the through holes in the radial direction as viewed in the axial direction, lubricant oil having flowed into the non-through grooves and thus having a reduced flow velocity can thus be satisfactorily discharged to the outside of the drum portion through the through holes.
- FIG. 1 is a schematic configuration diagram of a power transmission device including an automatic transmission having clutches as friction engagement elements according to an embodiment of the present disclosure.
- FIG. 2 is an operation table showing the relationship between shift speeds and the operating states of clutches and brakes of the automatic transmission included in the power transmission device of FIG. 1 .
- FIG. 3 is an enlarged sectional view showing a main part of the power transmission device of FIG. 1 .
- FIG. 4 is a sectional view taken along line A-B in FIG. 3 .
- FIG. 5 is a sectional view showing a main part of a clutch as a friction engagement element according to another embodiment.
- FIG. 6 is a sectional view showing a main part of a clutch as a friction engagement element according to a still another embodiment.
- FIG. 1 is a schematic configuration diagram of a power transmission device 20 including an automatic transmission 25 having a clutch C 1 as a friction engagement element according to an embodiment of the present disclosure.
- the power transmission device 20 shown in the figure is connected to a crankshaft of an engine, not shown, which is mounted on a front wheel drive vehicle, and can transmit power from the engine to right and left drive wheels, not shown.
- the power transmission device 20 includes a transmission case 22 , a starting device (torque converter) 23 , an oil pump 24 , the automatic transmission 25 , a gear mechanism (gear train) 28 , a differential gear (differential mechanism) 29 , etc. which are accommodated in the transmission case 22 .
- the starting device 23 included in the power transmission device 20 is configured as a torque converter having an input-side pump impeller 23 p connected to the crankshaft of the engine, an output-side turbine runner 23 t connected to an input shaft (input member) 26 of the automatic transmission 25 , a stator 23 s placed inside the pump impeller 23 p and the turbine runner 23 t to adjust the flow of hydraulic oil from the turbine runner 23 t to the pump impeller 23 p , a one-way clutch 23 o that allows the stator 23 s to rotate only in one direction, a lockup clutch 23 c , a damper mechanism 23 d , etc.
- the starting device 23 may be configured as a fluid coupling that does not have the stator 23 s.
- the oil pump 24 is configured as a gear pump having a pump assembly including a pump body and a pump cover, an external gear connected to the pump impeller 23 p of the starting device 23 via a hub, an internal gear meshing with the external gear, etc.
- the oil pump 24 is driven by the power from the engine to suck hydraulic oil (ATF) stored in an oil pan, not shown, to pressure-feed the sucked hydraulic oil to a hydraulic control device, not shown, which generates an oil pressure required by the starting device 23 and the automatic transmission 25 .
- ATF hydraulic oil
- the automatic transmission 25 is configured as a six-speed transmission. As shown in FIG. 1 , the automatic transmission 25 includes, in addition to the input shaft 26 , a double-pinion type first planetary gear mechanism 30 , a Ravigneaux type second planetary gear mechanism 35 , three clutches C 1 , C 2 , C 3 that change a power transmission path from the input side to the output side, two brakes B 1 , B 2 , and a one-way clutch F 1 .
- the first planetary gear mechanism 30 of the automatic transmission 25 has a sun gear 31 as an external gear, a ring gear 32 as an internal gear placed concentrically with the sun gear 31 , a plurality of pinion gears 33 meshing with the sun gear 31 and meshing with the ring gear 32 , and a planetary carrier 34 that rotatably (turnably) and revolvably holds the plurality of pinion gears 33 .
- the sun gear 31 of the first planetary gear mechanism 30 is fixed to the transmission case 22
- the ring gear 32 of the first planetary gear mechanism 30 is coupled to the input shaft 26 so as to be able to rotate together with the input shaft 26 .
- the second planetary gear mechanism 35 has a first sun gear 36 a and a second sun gear 36 b as external gears, a ring gear 37 as an internal gear placed concentrically with the first and second sun gears 36 a , 36 b , a plurality of short pinion gears 38 a meshing with the first sun gear 36 a , a plurality of long pinion gears 38 b meshing with the second sun gear 36 b and the plurality of short pinion gears 38 a and meshing with the ring gear 37 , and a planetary carrier 39 that rotatably (turnably) and revolvably holds the plurality of short pinion gears 38 a and the plurality of long pinion gears 38 b .
- the ring gear 37 of the second planetary gear mechanism 35 functions as an output member of the automatic transmission 25 , and the power transmitted from the input shaft 26 to the ring gear 37 is transmitted to the right and left driving wheels, not shown, via the gear mechanism 28 and the differential gear 29 .
- the planetary carrier 39 is supported by the transmission case 22 via the one-way clutch F 1 , and the one-way clutch F 1 allows the planetary carrier 39 to rotate only in one direction.
- the clutch C 1 is a multi-plate friction hydraulic clutch (friction engagement element) that has a hydraulic servo formed by a piston, a plurality of friction plates and separator plates, an oil chamber to which hydraulic oil is supplied, etc. and that can connect and disconnect the planetary carrier 34 of the first planetary gear mechanism 30 and the first sun gear 36 a of the second planetary gear mechanism 35 .
- the clutch C 2 is a multi-plate friction hydraulic clutch that has a hydraulic servo formed by a piston, a plurality of friction plates and separator plates, an oil chamber to which hydraulic oil is supplied, etc. and that can connect and disconnect the input shaft 26 and the planetary carrier 39 of the second planetary gear mechanism 35 .
- the clutch C 3 is a multi-plate friction hydraulic clutch that has a hydraulic servo formed by a piston, a plurality of friction plates and separator plates, an oil chamber to which hydraulic oil is supplied, etc. and that can connect and disconnect the planetary carrier 34 of the first planetary gear mechanism 30 and the second sun gear 36 b of the second planetary gear mechanism 35 .
- the brake B 1 is a multi-plate friction hydraulic brake that has a hydraulic servo formed by a plurality of friction plates and separator plates, an oil chamber to which hydraulic oil is supplied, etc. and that can hold the second sun gear 36 b of the second planetary gear mechanism 35 stationary to the transmission case 22 such that the second sun gear 36 b cannot rotate, and can release the second sun gear 36 b held stationary to the transmission case 22 .
- the brake B 2 is a multi-plate friction hydraulic brake that has a hydraulic servo formed by a plurality of friction plates and separator plates, an oil chamber to which hydraulic oil is supplied, etc. and that can hold the planetary carrier 39 of the second planetary gear mechanism 35 stationary to the transmission case 22 such that the planetary carrier 39 cannot rotate, and can release the planetary carrier 39 held stationary to the transmission case 22 .
- the one-way clutch F 1 includes an inner race coupled (fixed) to the planetary carrier 39 of the second planetary gear mechanism 35 , an outer race, a plurality of sprags, a plurality of springs (leaf springs), a cage, etc.
- the one-way clutch F 1 transmits torque via the sprags when the outer race rotates in one direction relative to the inner race.
- the one-way clutch F 1 rotates both the inner race and the outer race relative to each other when the outer race rotates in the other direction relative to the inner race.
- the one-way clutch F 1 may be a clutch having a configuration other than that of the sprag clutch, such as a roller clutch.
- FIG. 2 shows an operation table showing the relationship between shift speeds of the automatic transmission 25 and the operating states of the clutches C 1 to C 3 and the brakes B 1 , B 2 .
- the automatic transmission 25 provides first to sixth forward speeds and a reverse speed by bringing the clutches C 1 to C 3 and the brakes B 1 , B 2 into the states shown in the operation table of FIG. 2 .
- At least one of the clutches C 2 , C 3 other than the clutch C 1 , and the brakes B 1 , B 2 may be a meshing engagement element such as a dog clutch.
- FIG. 3 is an enlarged sectional view showing the clutch C 1 as a main part of the power transmission device 20
- FIG. 4 is a sectional view of the clutch C 1 taken along line A-B in FIG. 3 . Since the axial and radial directions of each component of the clutch C 1 match the axial and radial directions of the input shaft 26 of the automatic transmission 25 , the axial direction of the input shaft 26 is hereinafter simply referred to as the “axial direction,” and the radial direction of the input shaft 26 is hereinafter simply referred to as the “radial direction.”
- the clutch C 1 is configured as a wet multi-plate friction hydraulic clutch (friction engagement element) including a clutch drum (drum) 41 , a clutch hub (hub) 42 placed inside the clutch drum 41 , a plurality of friction plates 43 that are fitted in the clutch drum 41 , a plurality of separator plates 44 and a backing plate 45 which are fitted on the clutch hub 42 , a piston 46 that receives an engagement oil pressure supplied to an engagement oil chamber 47 and presses the friction plates 43 and the separator plates 44 to frictionally engage the friction plates 43 with the separator plates 44 , a cancel plate 48 that defines a cancel oil chamber 49 , and a plurality of return springs (coil springs) 50 that bias the piston 46 in such a direction that the piston 46 is separated from the friction plates 43 and the separator plates 44 .
- the clutch drum 41 has a cylindrical drum portion 411 and a sidewall portion 412 extended radially inward from one end (the left end in FIG. 3 ) of the drum portion 411 .
- Splines 411 s are formed in the inner periphery of the drum portion 411 .
- the inner periphery of the sidewall portion 412 is fixed to a drum-side coupling member 61 .
- the drum-side coupling member 61 has a first cylindrical portion 611 extending in the axial direction such that the input shaft 26 is surrounded, and a second cylindrical portion 612 having a larger diameter than the first cylindrical portion 611 .
- the first cylindrical portion 611 is coupled to the first sun gear 36 a of the second planetary gear mechanism 35 via a coupling member, not shown.
- the clutch drum 41 is thus coupled to the first sun gear 36 a of the second planetary gear mechanism 35 via the drum-side coupling member 61 and the coupling member, not shown.
- the clutch hub 42 has a cylindrical hub portion 421 and a sidewall portion 422 extending radially inward from one end located on the opposite side (the right side in FIG. 3 ) of the hub portion 421 from the clutch drum 41 .
- Splines 421 s are formed in the outer periphery of the hub portion 421 .
- the inner periphery of the sidewall portion 422 is fixed to the outer periphery of a hub-side coupling member 62 .
- the hub-side coupling member 62 is coupled to the planetary carrier 34 of the first planetary gear mechanism 30 .
- the clutch hub 42 is thus coupled to the planetary carrier 34 of the first planetary gear mechanism 30 via the hub-side coupling member 62 .
- the friction plate 43 is an annular member having a friction material 70 bonded to its both surfaces, and has a plurality of external teeth 43 s that are fitted in grooves 411 a of the splines 411 s formed in the inner periphery of the drum portion 411 of the clutch drum 41 .
- the friction material 70 is divided into a plurality of segments 71 , and the segments 71 are bonded to the friction plate 43 at intervals in the circumferential direction of the friction plate 43 .
- the separator plate 44 is an annular member both surfaces of which are smooth surfaces.
- the separator plates 44 are fitted on the splines 421 s formed in the hub portion 421 of the clutch hub 42 such that the separator plates 44 are arranged alternately with the plurality of friction plates 43 fitted in the drum portion 411 .
- the backing plate 45 is fitted on the splines 421 s of the hub portion 421 such that the backing plate 45 can contact the rightmost friction plate 43 in FIG. 3 .
- the backing plate 45 is supported in the axial direction by a snap ring fitted on the splines 421 s.
- the piston 46 is supported by the second cylindrical portion 612 of the drum-side coupling member 61 and the sidewall portion 412 of the clutch drum 41 such that the piston 46 can move in the axial direction.
- the piston 46 has external teeth formed in its outer periphery so as to be fitted on the splines 411 s formed in the drum portion 411 .
- a seal member is placed between the piston 46 and the second cylindrical portion 612 of the drum-side coupling member 61 and between the piston 46 and the sidewall portion 412 of the clutch drum 41 .
- the piston 46 together with the sidewall portion 412 of the clutch drum 41 and the second cylindrical portion 612 of the drum-side coupling member 61 thus defines the engagement oil chamber 47 to which an engagement oil pressure for engaging the clutch C 1 is supplied.
- the engagement oil chamber 47 is connected to the hydraulic control device, not shown, via an oil hole 61 a formed in the second cylindrical portion 612 of the drum-side coupling member 61 .
- the cancel plate 48 is supported in the radial direction by the piston 46 and the first cylindrical portion 611 of the drum-side coupling member 61 and is supported in the axial direction by a snap ring attached to the first cylindrical portion 611 at a position on the clutch hub 42 side (the right side in FIG. 3 ) of the piston 46 .
- a seal member is placed between the cancel plate 48 and the piston 46 .
- the cancel plate 48 together with the piston 46 and the drum-side coupling member 61 thus defines the cancel oil chamber 49 that cancels an oil pressure generated in the engagement oil chamber 47 .
- the cancel oil chamber 49 is connected to the hydraulic control device, not shown, via an oil hole 61 b formed in the drum-side coupling member 61 .
- the plurality of return springs 50 are placed between the piston 46 and the cancel plate 48 in the cancel oil chamber 49 . Instead of the plurality of coil springs, a single leaf spring may be used as the return springs 50 of the clutch C 1 .
- a structure for lubricating and cooling the plurality of friction plates 43 and the plurality of separator plates 44 of the clutch C 1 will be described below.
- a plurality of oil holes 61 c are formed in the first cylindrical portion 611 of the drum-side coupling member 61 such that the inside of the clutch hub 42 (the space between the clutch hub 42 and the cancel plate 48 ) communicates with the inside of the first cylindrical portion 611 .
- Each oil hole 61 c is connected to a lubricating system of the hydraulic control device, not shown, which supplies hydraulic oil as a lubricating/cooling medium to elements to be lubricated in the automatic transmission 25 .
- the hub portion 421 of the clutch hub 42 has a plurality of supply holes 421 o formed at intervals in the circumferential direction of the hub portion 421 .
- the plurality of supply holes 421 o are formed such that the space inside the hub portion 421 communicates with grooves of the splines 421 s formed in the hub portion 421 .
- the plurality of supply holes 421 o are formed at intervals in the axial direction so as to overlap each friction plate 43 as viewed in the radial direction.
- the plurality of supply holes 421 o may be formed at positions offset in the axial direction from the friction plates 43 as viewed in the radial direction.
- the plurality of oil holes 61 c of the drum-side coupling member 61 and the plurality of supply holes 421 o of the clutch hub 42 form a path for supplying hydraulic oil as a lubricating/cooling medium from the lubricating system of the hydraulic control device throughout the spaces between each friction plate 43 and each separator plate 44 .
- the drum portion 411 of the clutch drum 41 has a plurality of discharge holes (through holes) 411 o formed at intervals in the circumferential direction of the drum portion 411 .
- the plurality of discharge holes 411 o are formed such that the space outside the drum portion 411 communicates with the grooves 411 a of the splines 411 s formed in the drum portion 411 .
- the plurality of discharge holes 411 o are formed at intervals in the axial direction so as to overlap each friction plate 43 as viewed in the radial direction.
- the plurality of discharge holes 411 o form a path for discharging hydraulic oil that has lubricated and cooled the friction plates 43 and the separator plates 44 to the outside of the clutch drum 41 .
- the friction plate 43 has a plurality of oil grooves 72 formed at intervals in the circumferential direction of the friction plates 43 and extending in the radial direction.
- Each of the plurality of oil grooves 72 is formed between the segments 71 that adjoin each other and are included in the friction material 70 bonded to the friction plate 43 , and functions as a path for discharging hydraulic oil supplied throughout the spaces between the friction plate 43 and the separator plate 44 toward the drum portion 411 .
- Forming the plurality of oil grooves 72 in each friction plate 43 having the friction material 70 bonded thereto can more satisfactorily suppress peeling, chipping, etc.
- each of the plurality of oil grooves 72 is formed radially inward of its adjacent external tooth 43 s of the friction plate 43 , and is located next to the adjacent external tooth 43 s in the radial direction as viewed in the axial direction of the friction plate 43 .
- each oil groove 72 can be located next to its adjacent discharge hole 411 o in the radial direction as viewed in the axial direction.
- each oil groove 72 which is located on the inner peripheral side of the friction plate 43 (hereinafter simply referred to as the “inner peripheral side”) is formed so as to narrow as closer to the outer peripheral side of the friction plate 43 (hereinafter simply referred to as the “outer peripheral side”).
- the openings 72 o can be easily formed by cutting out a part on the inner peripheral side of each segment 71 of the friction material 70 .
- each of the plurality of oil grooves 72 is formed next to its adjacent discharge hole 411 o in the radial direction as viewed in the axial direction.
- the hydraulic oil can thus be smoothly guided from each oil groove 72 to the groove 411 a (the discharge hole 411 o adjacent to the oil groove 72 ) of the splines 411 s of the drum portion 411 in which the external tooth 43 s adjacent to the oil groove 72 is fitted, and can be satisfactorily discharged to the outside of the drum portion 411 through each discharge hole 411 o . Since the plurality of discharge holes 411 o are formed in the drum portion 411 so as to overlap each friction plate 43 as viewed in the radial direction, the hydraulic oil can be more smoothly guided from each oil groove 72 to its adjacent discharge hole 411 o and can be more satisfactorily discharged to the outside of the drum portion 411 through each discharge hole 411 o.
- each oil groove 72 is formed so as to narrow as closer to the outer peripheral side. This can increase the flow velocity of the hydraulic oil that has flowed into the opening 72 o on the inner peripheral side of each oil groove 72 . As a result, the hydraulic oil can flow straighter in each oil groove 72 , and the hydraulic oil can be more satisfactorily discharged to the outside of the drum portion 411 through the oil grooves 72 and the discharge holes 411 o adjacent to the oil grooves 72 .
- the hydraulic oil can be more satisfactorily controlled not to stay inside the drum portion 411 .
- This can more satisfactorily suppress generation of drag torque due to viscous shear resistance of hydraulic oil that is present between each friction plate 43 and each separator plate 44 when the friction plates 43 and the separator plates 44 are in a disengaged state.
- hydraulic oil is distributed more smoothly, the capability of cooling the friction plates 43 and the separator plates 44 when the friction plates 43 and the separator plates 44 are in an engaged state can also be improved.
- hydraulic oil is controlled not to stay inside the drum portion 411 , peeling, chipping, etc. of the friction materials 70 bonded to the friction plates 43 due to the impact with the hydraulic oil can be satisfactorily suppressed.
- the annular friction plates 43 each having the friction material 70 attached to its surfaces are fitted in the inner periphery of the cylindrical drum portion 411 of the clutch drum 41 , and the annular separator plates 44 capable of frictionally engaging with the friction plates 43 are fitted on the outer periphery of the cylindrical hub portion 421 of the clutch hub 42 .
- the drum portion 411 has the splines 411 s on which the plurality of external teeth 43 s of the friction plates 43 are fitted, and the plurality of discharge holes (through holes) 411 o formed in the grooves 411 a of the splines 411 s .
- each friction plate 43 has the plurality of oil grooves 72 formed at intervals in the circumferential direction of the friction plate 43 and extending in the radial direction of the friction plate 43 .
- the plurality of oil grooves 72 are thus formed in each friction plate 43 having the friction materials 70 attached thereto. This can more satisfactorily suppress peeling, chipping, etc. of the friction materials 70 when the friction plates 43 frictionally engage with the separator plates 44 with the friction material 70 interposed therebetween, as compared to the case where the plurality of oil grooves 72 are formed in the separator plates 44 .
- Each of the plurality of oil grooves 72 is formed next to its adjacent external tooth 43 s in the radial direction as viewed in the axial direction of the friction plates 43 .
- Hydraulic oil as a lubricating/cooling medium that is supplied throughout the spaces between the friction material 70 of each friction plate 43 and each separator plate 44 can thus be smoothly guided from each oil groove 72 to the groove 411 a (the discharge hole 411 o adjacent to the oil groove 72 ) of the splines 411 s of the drum portion 411 in which the external tooth 43 s adjacent to the oil groove 72 is fitted, can be satisfactorily discharged to the outside of the drum portion 411 through each discharge hole 411 o , and can be more satisfactorily controlled not to stay inside the drum portion 411 .
- Each of the plurality of oil grooves 72 is formed next to its adjacent discharge hole 411 o in the radial direction as viewed in the axial direction of the friction plates 43 , and the plurality of discharge holes 411 o are formed in the drum portion 411 so as to overlap the friction plates 43 in the axial direction as viewed in the radial direction. Hydraulic oil can thus be more smoothly guided from each oil groove 72 of each friction plate 43 to its adjacent discharge hole 411 o , and can be more satisfactorily discharged to the outside of the drum portion 411 through each discharge hole 411 o .
- the plurality of discharge holes 411 o may be formed at the positions offset in the axial direction from the friction plates 43 as viewed in the radial direction.
- the drum portion 411 has the splines 411 s formed in the inner periphery thereof, and the plurality of discharge holes 411 o are formed such that the outside of the drum portion 411 communicates with the grooves 411 a of the splines 411 s .
- Each friction plate 43 has the plurality of external teeth 43 s that are fitted in the grooves 411 a of the splines 411 s , and each of the plurality of oil grooves 72 is formed radially inward of its adjacent external tooth 43 s .
- each oil groove 72 can be located next to its adjacent discharge hole 411 o in the radial direction as viewed in the axial direction.
- the openings 72 o of the plurality of oil grooves 72 which are located on the inner peripheral side of each friction plate 43 are formed so as to narrow as closer to the outer peripheral side of the friction plate 43 .
- This can increase the flow velocity of hydraulic oil flowing in the oil grooves 72 .
- the hydraulic oil can thus flow straighter in each oil groove 72 , and the hydraulic oil can be more satisfactorily discharged to the outside of the drum portion 411 through the oil grooves 72 and the discharge holes 411 o adjacent to the oil grooves 72 .
- the entire oil grooves 72 may be formed so as to narrow from the inner peripheral side as closer to the outer peripheral side. The hydraulic oil can thus flow much straighter in each oil groove 72 .
- FIG. 5 is a sectional view showing a clutch C 1 B as a friction engagement element according to another embodiment.
- the clutch C 1 B includes, instead of the friction materials 70 of the clutch C 1 , friction materials 70 B each having segments 71 B wider than the segments 71 of the friction materials 70 .
- Each friction material 70 B has a plurality of non-through grooves 73 that are formed in each segment 71 B such that the non-through grooves 73 are located between the oil grooves 72 adjoining each other and that are open on the inner peripheral side of the friction plate 43 .
- the non-through grooves 73 may be formed by cutting out a part on the inner peripheral side of each segment 71 or may be formed by pressing each segment 71 .
- each friction plate 43 and each separator plate 44 are subjected to a force in such a direction that the friction plate 43 and the separator plate 44 are separated from each other due to the oil pressure generated in the non-through grooves 73 . Clearance between each friction plate 43 and each separator plate 44 can thus be more properly maintained, which can further reduce drag torque that is generated between each friction plate 43 and each separator plate 44 .
- Each of the plurality of non-through grooves 73 is formed next to its adjacent external tooth 43 s and its adjacent discharge hole 411 o in the radial direction as viewed in the axial direction. As shown by thick dashed arrows in FIG.
- each segment 71 The shape and position of the non-through groove 73 of each segment 71 are not limited to those shown in FIG. 5 .
- a plurality of non-through grooves 73 may be formed in each segment 71 . In this case, not every non-through groove 73 need necessarily be formed next to its adjacent discharge hole 411 o in the radial direction as viewed in the axial direction.
- hydraulic oil can be satisfactorily controlled not to flow over the oil grooves 72 C and thus not to be present between the friction material 70 C and the separator plate 44 when the hydraulic oil flows in the opposite direction to the rotation direction of the friction plates 43 .
- This can more satisfactorily suppress generation of drag torque between each friction plate 43 and each separator plate 44 .
- hydraulic oil that has flowed along each oil groove 72 C to the outer peripheral side is discharged to the outside of the drum portion 411 thorough the discharge holes 411 o of the drum portion 411 .
- Each oil groove 72 C may be formed such that the entire oil groove 72 C including the opening 72 o widens from the inner peripheral side as closer to the outer peripheral side, or may be formed such that the entire oil groove 72 C including the opening 72 o is tilted in one direction (the opposite direction to the primary rotation direction of the friction plates 43 ) from the inner peripheral side as closer to the outer peripheral side.
- the present disclosure is applied to the clutches C 1 , C 1 B, and C 1 C as wet multi-plate friction hydraulic clutches capable of connecting and disconnecting the planetary carrier 34 of the first planetary gear mechanism 30 and the first sun gear 36 a of the second planetary gear mechanism 35 in the automatic transmission 25 .
- the present disclosure may be applied to any clutch or brake as long as it is a wet friction engagement element including a drum having a cylindrical drum portion, a hub having a cylindrical hub portion, an annular friction plate fitted in the inner periphery of the drum portion and having a friction material bonded to its surface, and an annular separator plate fitted on the outer periphery of the hub portion and capable of frictionally engaging with the friction plate.
- the friction materials 70 , 70 B, and 70 C are not limited to those divided into the plurality of segments 71 , 71 B, or 71 C, and may be integral friction materials having an annular shape.
- the plurality of oil grooves 72 , 72 C can be formed by pressing the annular friction material. Not every one of the plurality of oil grooves 72 , 72 C need necessarily be formed next to its adjacent discharge hole 411 o of the drum portion 411 in the radial direction as viewed in the axial direction.
- the clutch drum 41 having the cylindrical drum portion 411 corresponds to the “drum”
- the clutch hub 42 having the cylindrical hub portion 421 corresponds to the “hub”
- the annular friction plate 43 fitted in the inner periphery of the drum portion 411 and having the friction materials 70 bonded to its surfaces corresponds to the “friction plate”
- the annular separator plate 44 fitted on the outer periphery of the hub portion 421 and capable of frictionally engaging with the friction plate 43 corresponds to the “separator plate”
- the clutch C 1 as a wet multi-plate friction hydraulic clutch corresponds to the “friction engagement element”
- the plurality of discharge holes 411 o formed at intervals in the circumferential direction of the drum portion correspond to the “plurality of through holes”
- the present disclosure is applicable to manufacturing industries of friction engagement elements, automatic transmissions including the same, etc.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Mechanical Operated Clutches (AREA)
- Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)
Abstract
A wet friction engagement element including a drum having a cylindrical drum portion; a hub having a cylindrical hub portion; an annular friction plate fitted in an inner periphery of the drum portion and having a friction material bonded to its surface; and an annular separator plate fitted on an outer periphery of the hub portion and capable of frictionally engaging with the friction plate.
Description
- The present disclosure relates to wet friction engagement elements including annular friction plates each having a friction material bonded to its surface and annular separator plates capable of frictionally engaging with the friction plates.
- Conventionally, wet multi-plate clutches including annular friction plates meshing with splines formed in the outer periphery of a hub and each having a friction material bonded thereto and annular separator plates meshing with splines formed in the inner periphery of a drum are known as this type of friction engagement element (see, e.g., Japanese Patent Application Publication No. 2000-145819). In this wet multi-plate clutch, a plurality of lubricant oil supply holes are formed in the hub. A plurality of oil through grooves extending from the inner peripheral edge to the outer peripheral edge of the friction material of the friction plate are formed such that their openings at the inner peripheral edge face lubricant oil supply holes. This allows the lubricant oil that is supplied from the lubricant oil supply holes throughout the spaces between each friction plate and each separator plate via the oil through grooves to flow more smoothly, and thus allows the lubricant oil to be discharged from the spaces between each friction plate and each separator plate in a more desirable manner.
- As this type of friction engagement element, a wet multi-plate clutch is also known which includes a plurality of metal plates fitted in the inner periphery of an input drum and a plurality of facing plates fitted on the outer periphery of an input clutch hub and each having a friction material facing bonded to its both surfaces (see, e.g., Japanese Patent Application Publication No. 2002-106597). In this wet multi-plate clutch, oil grooves are formed in the surface of each metal plate so as to extend from the inner radial side toward the outer radial side, and clearance extending in the circumferential direction is provided between the inner periphery of the input drum and the outer radial ends of the oil grooves of each metal plate. Lubricant oil used to lubricate the metal plates and the facing plates thus flows in the axial direction of the wet multi-plate clutch from each oil groove to the spaces between the input drum and the plurality of metal plates through the clearance, and is discharged to the outside of the input drum through oil discharge openings formed in the input drum. A method in which a plurality of segments made of a friction material are bonded at intervals to a core plate having external teeth and a plurality of grooves are formed between the segments is also known as a method for manufacturing a wet friction clutch plate for use in this type of friction engagement element (see, e.g., Japanese Patent Application Publication No. 2004-176915).
- In the wet multi-plate clutch described in Japanese Patent Application Publication No. 2000-145819, lubricant oil can be discharged from the spaces between each friction plate and each separator plate in a more desirable manner. However, if the lubricant oil is not satisfactorily discharged to the outside of the drum and stays inside the drum, a relatively large amount of lubricant oil is present between each friction plate and each separator plate. Accordingly, drag torque due to viscous shear resistance of the lubricant oil may not be satisfactorily reduced when the wet multi-plate clutch is in a disengaged state. In the wet multi-plate clutch described in Japanese Patent Application Publication No. 2002-106597, lubricant oil having flowed in the oil grooves and the clearance can be discharged to the outside of the input drum through the openings formed in the input drum. In this wet multi-plate clutch, however, since the oil grooves are formed in the metal plates, peeling, chipping, etc. of the friction materials may occur as the edges of the oil grooves contact the friction materials of the facing plates when the facing plates frictionally engage with the metal plates.
- The present disclosure according to an exemplary aspect further reduces drag torque that is generated when a friction engagement element is not engaged, while more satisfactorily protecting a friction material bonded to a friction plate.
- A friction engagement element according to an exemplary aspect of the present disclosure is a wet friction engagement element including a drum having a cylindrical drum portion, a hub having a cylindrical hub portion, an annular friction plate fitted in an inner periphery of the drum portion and having a friction material bonded to its surface, and an annular separator plate fitted on an outer periphery of the hub portion and capable of frictionally engaging with the friction plate, wherein the drum portion has splines on which a plurality of external teeth formed in the friction plate are fitted, and a plurality of through holes formed in grooves of the splines, the friction plate has a plurality of oil grooves formed at intervals in a circumferential direction of the friction plate and extending in a radial direction of the friction plate, and each of the plurality of oil grooves is located next to its adjacent one of the external teeth in the radial direction as viewed in an axial direction of the friction plate.
- In this friction engagement element, the annular friction plate having the friction material bonded to its surface is fitted in the inner periphery of the cylindrical drum portion of the drum, and the annular separator plate capable of frictionally engaging with the friction plate is fitted on the outer periphery of the cylindrical hub portion of the hub. The drum portion has the splines on which the plurality of external teeth formed in the friction plate are fitted, and the plurality of through holes formed in the grooves of the splines. The friction plate has the plurality of oil grooves formed at intervals in the circumferential direction of the friction plate and extending in the radial direction of the friction plate. Forming the plurality of oil grooves in the friction plate having the friction material bonded thereto can more satisfactorily suppress peeling, chipping, etc. of the friction material when the friction plate frictionally engages with the separator plate with the friction material interposed therebetween, as compared to the case where the plurality of oil grooves are formed in the separator plate. Each of the plurality of oil grooves is formed next to its adjacent one of the external teeth in the radial direction as viewed in an axial direction of the friction plate. Lubricant oil supplied throughout the spaces between the friction material of the friction plate and the separator plate can thus be smoothly guided from each oil groove to the groove of the splines of the drum portion in which the external tooth adjacent to the oil groove is fitted, and can be satisfactorily discharged from each through hole to the outside of the drum portion. The lubricant oil can thus be more satisfactorily controlled not to stay inside the drum portion. This can more satisfactorily suppress generation of drag torque due to viscous shear resistance of lubricant oil that is present between the friction plate and the separator plate when the friction plate and the separator plate are in a disengaged state. In this friction engagement element, the friction material bonded to the friction plate can therefore be more satisfactorily protected, and drag torque that is generated when the friction engagement element is in a disengaged state can further be reduced.
- Each of the plurality of oil grooves may be located next to its adjacent one of the through holes in the radial direction as viewed in the axial direction of the friction plate, and the plurality of through holes may be formed in the drum portion so as to overlap the friction plate as viewed in the radial direction. The lubricant oil can thus be more smoothly guided from each oil groove to the through hole adjacent to the oil groove, and the lubricant oil can be more satisfactorily discharged to the outside of the drum portion through each through hole.
- The drum portion may have the splines formed in the inner periphery, the plurality of through holes may be formed such that outside of the drum portion communicates with the grooves of the splines, the friction plate may have the plurality of external teeth that are fitted in the grooves of the splines, and each of the plurality of oil grooves may be formed radially inward of its adjacent one of the external teeth. By fitting the external teeth of the friction plate which are located radially outward of the oil grooves in the grooves of the splines of the drum portion which communicate with the through holes, each oil groove can be located next to its adjacent one of the through holes in the radial direction as viewed in the axial direction.
- An opening of the oil groove which is located on an inner peripheral side of the friction plate may be formed so as to narrow as closer to an outer peripheral side of the friction plate. This can increase the flow velocity of the lubricant oil flowing in the oil grooves. The lubricant oil can thus flow straighter in each oil groove, and the lubricant oil can be more satisfactorily discharged to the outside of the drum portion through the oil grooves and the through holes adjacent to the oil grooves.
- The friction material may have a plurality of non-through grooves each formed between the oil grooves adjoining each other and each opening on the inner peripheral side of the friction plate, and each of the plurality of non-through grooves may be formed next to its adjacent one of the through holes in the radial direction as viewed in the axial direction. The friction plate and the separator plate are thus subjected to a force in such a direction that the friction plate and the separator plate are separated from each other due to an oil pressure of the lubricant oil having flowed into the non-through grooves of the friction material. Clearance between the friction plate and the separator plate can thus be more properly maintained, which can further reduce drag torque that is generated between the friction plate and the separator plate. Moreover, since each of the non-through grooves is formed next to its adjacent one of the through holes in the radial direction as viewed in the axial direction, lubricant oil having flowed into the non-through grooves and thus having a reduced flow velocity can thus be satisfactorily discharged to the outside of the drum portion through the through holes.
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FIG. 1 is a schematic configuration diagram of a power transmission device including an automatic transmission having clutches as friction engagement elements according to an embodiment of the present disclosure. -
FIG. 2 is an operation table showing the relationship between shift speeds and the operating states of clutches and brakes of the automatic transmission included in the power transmission device ofFIG. 1 . -
FIG. 3 is an enlarged sectional view showing a main part of the power transmission device ofFIG. 1 . -
FIG. 4 is a sectional view taken along line A-B inFIG. 3 . -
FIG. 5 is a sectional view showing a main part of a clutch as a friction engagement element according to another embodiment. -
FIG. 6 is a sectional view showing a main part of a clutch as a friction engagement element according to a still another embodiment. - Modes for carrying out the present disclosure will be described with reference to the accompanying drawings.
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FIG. 1 is a schematic configuration diagram of apower transmission device 20 including anautomatic transmission 25 having a clutch C1 as a friction engagement element according to an embodiment of the present disclosure. Thepower transmission device 20 shown in the figure is connected to a crankshaft of an engine, not shown, which is mounted on a front wheel drive vehicle, and can transmit power from the engine to right and left drive wheels, not shown. As shown in the figure, thepower transmission device 20 includes atransmission case 22, a starting device (torque converter) 23, anoil pump 24, theautomatic transmission 25, a gear mechanism (gear train) 28, a differential gear (differential mechanism) 29, etc. which are accommodated in thetransmission case 22. - The
starting device 23 included in thepower transmission device 20 is configured as a torque converter having an input-side pump impeller 23 p connected to the crankshaft of the engine, an output-side turbine runner 23 t connected to an input shaft (input member) 26 of theautomatic transmission 25, astator 23 s placed inside thepump impeller 23 p and theturbine runner 23 t to adjust the flow of hydraulic oil from theturbine runner 23 t to thepump impeller 23 p, a one-way clutch 23 o that allows thestator 23 s to rotate only in one direction, alockup clutch 23 c, adamper mechanism 23 d, etc. Thestarting device 23 may be configured as a fluid coupling that does not have thestator 23 s. - The
oil pump 24 is configured as a gear pump having a pump assembly including a pump body and a pump cover, an external gear connected to thepump impeller 23 p of thestarting device 23 via a hub, an internal gear meshing with the external gear, etc. Theoil pump 24 is driven by the power from the engine to suck hydraulic oil (ATF) stored in an oil pan, not shown, to pressure-feed the sucked hydraulic oil to a hydraulic control device, not shown, which generates an oil pressure required by thestarting device 23 and theautomatic transmission 25. - The
automatic transmission 25 is configured as a six-speed transmission. As shown inFIG. 1 , theautomatic transmission 25 includes, in addition to theinput shaft 26, a double-pinion type firstplanetary gear mechanism 30, a Ravigneaux type secondplanetary gear mechanism 35, three clutches C1, C2, C3 that change a power transmission path from the input side to the output side, two brakes B1, B2, and a one-way clutch F1. - The first
planetary gear mechanism 30 of theautomatic transmission 25 has asun gear 31 as an external gear, aring gear 32 as an internal gear placed concentrically with thesun gear 31, a plurality ofpinion gears 33 meshing with thesun gear 31 and meshing with thering gear 32, and aplanetary carrier 34 that rotatably (turnably) and revolvably holds the plurality ofpinion gears 33. As shown in the figure, thesun gear 31 of the firstplanetary gear mechanism 30 is fixed to thetransmission case 22, and thering gear 32 of the firstplanetary gear mechanism 30 is coupled to theinput shaft 26 so as to be able to rotate together with theinput shaft 26. - The second
planetary gear mechanism 35 has a first sun gear 36 a and a second sun gear 36 b as external gears, aring gear 37 as an internal gear placed concentrically with the first and second sun gears 36 a, 36 b, a plurality ofshort pinion gears 38 a meshing with the first sun gear 36 a, a plurality oflong pinion gears 38 b meshing with the second sun gear 36 b and the plurality ofshort pinion gears 38 a and meshing with thering gear 37, and aplanetary carrier 39 that rotatably (turnably) and revolvably holds the plurality ofshort pinion gears 38 a and the plurality oflong pinion gears 38 b. Thering gear 37 of the secondplanetary gear mechanism 35 functions as an output member of theautomatic transmission 25, and the power transmitted from theinput shaft 26 to thering gear 37 is transmitted to the right and left driving wheels, not shown, via thegear mechanism 28 and thedifferential gear 29. Theplanetary carrier 39 is supported by thetransmission case 22 via the one-way clutch F1, and the one-way clutch F1 allows theplanetary carrier 39 to rotate only in one direction. - The clutch C1 is a multi-plate friction hydraulic clutch (friction engagement element) that has a hydraulic servo formed by a piston, a plurality of friction plates and separator plates, an oil chamber to which hydraulic oil is supplied, etc. and that can connect and disconnect the
planetary carrier 34 of the firstplanetary gear mechanism 30 and the first sun gear 36 a of the secondplanetary gear mechanism 35. The clutch C2 is a multi-plate friction hydraulic clutch that has a hydraulic servo formed by a piston, a plurality of friction plates and separator plates, an oil chamber to which hydraulic oil is supplied, etc. and that can connect and disconnect theinput shaft 26 and theplanetary carrier 39 of the secondplanetary gear mechanism 35. The clutch C3 is a multi-plate friction hydraulic clutch that has a hydraulic servo formed by a piston, a plurality of friction plates and separator plates, an oil chamber to which hydraulic oil is supplied, etc. and that can connect and disconnect theplanetary carrier 34 of the firstplanetary gear mechanism 30 and the second sun gear 36 b of the secondplanetary gear mechanism 35. - The brake B1 is a multi-plate friction hydraulic brake that has a hydraulic servo formed by a plurality of friction plates and separator plates, an oil chamber to which hydraulic oil is supplied, etc. and that can hold the second sun gear 36 b of the second
planetary gear mechanism 35 stationary to thetransmission case 22 such that the second sun gear 36 b cannot rotate, and can release the second sun gear 36 b held stationary to thetransmission case 22. The brake B2 is a multi-plate friction hydraulic brake that has a hydraulic servo formed by a plurality of friction plates and separator plates, an oil chamber to which hydraulic oil is supplied, etc. and that can hold theplanetary carrier 39 of the secondplanetary gear mechanism 35 stationary to thetransmission case 22 such that theplanetary carrier 39 cannot rotate, and can release theplanetary carrier 39 held stationary to thetransmission case 22. - The one-way clutch F1 includes an inner race coupled (fixed) to the
planetary carrier 39 of the secondplanetary gear mechanism 35, an outer race, a plurality of sprags, a plurality of springs (leaf springs), a cage, etc. The one-way clutch F1 transmits torque via the sprags when the outer race rotates in one direction relative to the inner race. The one-way clutch F1 rotates both the inner race and the outer race relative to each other when the outer race rotates in the other direction relative to the inner race. The one-way clutch F1 may be a clutch having a configuration other than that of the sprag clutch, such as a roller clutch. - The clutches C1 to C3 and the brake B1, B2 operate according to supply and discharge of hydraulic oil by the hydraulic control device, not shown.
FIG. 2 shows an operation table showing the relationship between shift speeds of theautomatic transmission 25 and the operating states of the clutches C1 to C3 and the brakes B1, B2. Theautomatic transmission 25 provides first to sixth forward speeds and a reverse speed by bringing the clutches C1 to C3 and the brakes B1, B2 into the states shown in the operation table ofFIG. 2 . At least one of the clutches C2, C3 other than the clutch C1, and the brakes B1, B2 may be a meshing engagement element such as a dog clutch. - The clutch C1 included in the
automatic transmission 25 will be described in detail below with reference toFIGS. 3 and 4 .FIG. 3 is an enlarged sectional view showing the clutch C1 as a main part of thepower transmission device 20, andFIG. 4 is a sectional view of the clutch C1 taken along line A-B inFIG. 3 . Since the axial and radial directions of each component of the clutch C1 match the axial and radial directions of theinput shaft 26 of theautomatic transmission 25, the axial direction of theinput shaft 26 is hereinafter simply referred to as the “axial direction,” and the radial direction of theinput shaft 26 is hereinafter simply referred to as the “radial direction.” - The clutch C1 is configured as a wet multi-plate friction hydraulic clutch (friction engagement element) including a clutch drum (drum) 41, a clutch hub (hub) 42 placed inside the
clutch drum 41, a plurality offriction plates 43 that are fitted in theclutch drum 41, a plurality ofseparator plates 44 and abacking plate 45 which are fitted on theclutch hub 42, apiston 46 that receives an engagement oil pressure supplied to anengagement oil chamber 47 and presses thefriction plates 43 and theseparator plates 44 to frictionally engage thefriction plates 43 with theseparator plates 44, a cancelplate 48 that defines a canceloil chamber 49, and a plurality of return springs (coil springs) 50 that bias thepiston 46 in such a direction that thepiston 46 is separated from thefriction plates 43 and theseparator plates 44. - The
clutch drum 41 has acylindrical drum portion 411 and asidewall portion 412 extended radially inward from one end (the left end inFIG. 3 ) of thedrum portion 411.Splines 411 s are formed in the inner periphery of thedrum portion 411. The inner periphery of thesidewall portion 412 is fixed to a drum-side coupling member 61. The drum-side coupling member 61 has a firstcylindrical portion 611 extending in the axial direction such that theinput shaft 26 is surrounded, and a secondcylindrical portion 612 having a larger diameter than the firstcylindrical portion 611. The firstcylindrical portion 611 is coupled to the first sun gear 36 a of the secondplanetary gear mechanism 35 via a coupling member, not shown. Theclutch drum 41 is thus coupled to the first sun gear 36 a of the secondplanetary gear mechanism 35 via the drum-side coupling member 61 and the coupling member, not shown. - The
clutch hub 42 has acylindrical hub portion 421 and asidewall portion 422 extending radially inward from one end located on the opposite side (the right side inFIG. 3 ) of thehub portion 421 from theclutch drum 41.Splines 421 s are formed in the outer periphery of thehub portion 421. The inner periphery of thesidewall portion 422 is fixed to the outer periphery of a hub-side coupling member 62. The hub-side coupling member 62 is coupled to theplanetary carrier 34 of the firstplanetary gear mechanism 30. Theclutch hub 42 is thus coupled to theplanetary carrier 34 of the firstplanetary gear mechanism 30 via the hub-side coupling member 62. - As shown in
FIGS. 3 and 4 , thefriction plate 43 is an annular member having afriction material 70 bonded to its both surfaces, and has a plurality ofexternal teeth 43 s that are fitted ingrooves 411 a of thesplines 411 s formed in the inner periphery of thedrum portion 411 of theclutch drum 41. As shown inFIG. 4 , thefriction material 70 is divided into a plurality ofsegments 71, and thesegments 71 are bonded to thefriction plate 43 at intervals in the circumferential direction of thefriction plate 43. Theseparator plate 44 is an annular member both surfaces of which are smooth surfaces. Theseparator plates 44 are fitted on thesplines 421 s formed in thehub portion 421 of theclutch hub 42 such that theseparator plates 44 are arranged alternately with the plurality offriction plates 43 fitted in thedrum portion 411. Thebacking plate 45 is fitted on thesplines 421 s of thehub portion 421 such that thebacking plate 45 can contact therightmost friction plate 43 inFIG. 3 . Thebacking plate 45 is supported in the axial direction by a snap ring fitted on thesplines 421 s. - The
piston 46 is supported by the secondcylindrical portion 612 of the drum-side coupling member 61 and thesidewall portion 412 of theclutch drum 41 such that thepiston 46 can move in the axial direction. Thepiston 46 has external teeth formed in its outer periphery so as to be fitted on thesplines 411 s formed in thedrum portion 411. A seal member is placed between thepiston 46 and the secondcylindrical portion 612 of the drum-side coupling member 61 and between thepiston 46 and thesidewall portion 412 of theclutch drum 41. Thepiston 46 together with thesidewall portion 412 of theclutch drum 41 and the secondcylindrical portion 612 of the drum-side coupling member 61 thus defines theengagement oil chamber 47 to which an engagement oil pressure for engaging the clutch C1 is supplied. Theengagement oil chamber 47 is connected to the hydraulic control device, not shown, via anoil hole 61 a formed in the secondcylindrical portion 612 of the drum-side coupling member 61. - The cancel
plate 48 is supported in the radial direction by thepiston 46 and the firstcylindrical portion 611 of the drum-side coupling member 61 and is supported in the axial direction by a snap ring attached to the firstcylindrical portion 611 at a position on theclutch hub 42 side (the right side inFIG. 3 ) of thepiston 46. A seal member is placed between the cancelplate 48 and thepiston 46. The cancelplate 48 together with thepiston 46 and the drum-side coupling member 61 thus defines the canceloil chamber 49 that cancels an oil pressure generated in theengagement oil chamber 47. The canceloil chamber 49 is connected to the hydraulic control device, not shown, via anoil hole 61 b formed in the drum-side coupling member 61. The plurality of return springs 50 are placed between thepiston 46 and the cancelplate 48 in the canceloil chamber 49. Instead of the plurality of coil springs, a single leaf spring may be used as the return springs 50 of the clutch C1. - A structure for lubricating and cooling the plurality of
friction plates 43 and the plurality ofseparator plates 44 of the clutch C1 will be described below. As shown inFIG. 3 , a plurality of oil holes 61 c are formed in the firstcylindrical portion 611 of the drum-side coupling member 61 such that the inside of the clutch hub 42 (the space between theclutch hub 42 and the cancel plate 48) communicates with the inside of the firstcylindrical portion 611. Eachoil hole 61 c is connected to a lubricating system of the hydraulic control device, not shown, which supplies hydraulic oil as a lubricating/cooling medium to elements to be lubricated in theautomatic transmission 25. - As shown in
FIG. 3 , thehub portion 421 of theclutch hub 42 has a plurality ofsupply holes 421 o formed at intervals in the circumferential direction of thehub portion 421. The plurality ofsupply holes 421 o are formed such that the space inside thehub portion 421 communicates with grooves of thesplines 421 s formed in thehub portion 421. As shown inFIG. 3 , the plurality ofsupply holes 421 o are formed at intervals in the axial direction so as to overlap eachfriction plate 43 as viewed in the radial direction. The plurality ofsupply holes 421 o may be formed at positions offset in the axial direction from thefriction plates 43 as viewed in the radial direction. The plurality of oil holes 61 c of the drum-side coupling member 61 and the plurality ofsupply holes 421 o of theclutch hub 42 form a path for supplying hydraulic oil as a lubricating/cooling medium from the lubricating system of the hydraulic control device throughout the spaces between eachfriction plate 43 and eachseparator plate 44. - The
drum portion 411 of theclutch drum 41 has a plurality of discharge holes (through holes) 411 o formed at intervals in the circumferential direction of thedrum portion 411. As shown inFIG. 4 , the plurality of discharge holes 411 o are formed such that the space outside thedrum portion 411 communicates with thegrooves 411 a of thesplines 411 s formed in thedrum portion 411. As shown inFIG. 3 , the plurality of discharge holes 411 o are formed at intervals in the axial direction so as to overlap eachfriction plate 43 as viewed in the radial direction. The plurality of discharge holes 411 o form a path for discharging hydraulic oil that has lubricated and cooled thefriction plates 43 and theseparator plates 44 to the outside of theclutch drum 41. - As shown in
FIG. 4 , thefriction plate 43 has a plurality ofoil grooves 72 formed at intervals in the circumferential direction of thefriction plates 43 and extending in the radial direction. Each of the plurality ofoil grooves 72 is formed between thesegments 71 that adjoin each other and are included in thefriction material 70 bonded to thefriction plate 43, and functions as a path for discharging hydraulic oil supplied throughout the spaces between thefriction plate 43 and theseparator plate 44 toward thedrum portion 411. Forming the plurality ofoil grooves 72 in eachfriction plate 43 having thefriction material 70 bonded thereto can more satisfactorily suppress peeling, chipping, etc. of thefriction material 70 when thefriction plate 43 frictionally engages with theseparator plate 44 with thefriction material 70 interposed therebetween, as compared to the case where the plurality ofoil grooves 72 are formed in eachseparator plate 44. Thefriction materials 70 bonded to thefriction plates 43 can therefore be more satisfactorily protected. - As shown in
FIG. 4 , each of the plurality ofoil grooves 72 is formed radially inward of its adjacentexternal tooth 43 s of thefriction plate 43, and is located next to the adjacentexternal tooth 43 s in the radial direction as viewed in the axial direction of thefriction plate 43. By fitting theexternal teeth 43 s located radially outward of theoil grooves 72 in thegrooves 411 a of thesplines 411 s of thedrum portion 411 which communicate with the discharge holes 411 o, eachoil groove 72 can be located next to itsadjacent discharge hole 411 o in the radial direction as viewed in the axial direction. An opening 72 o of eachoil groove 72 which is located on the inner peripheral side of the friction plate 43 (hereinafter simply referred to as the “inner peripheral side”) is formed so as to narrow as closer to the outer peripheral side of the friction plate 43 (hereinafter simply referred to as the “outer peripheral side”). The openings 72 o can be easily formed by cutting out a part on the inner peripheral side of eachsegment 71 of thefriction material 70. - In the clutch C1 configured as described above, when hydraulic oil is supplied from the hydraulic control device to the
engagement oil chamber 47 via theoil hole 61 a and the oil pressure in theengagement oil chamber 47 increases accordingly, thepiston 46 moves toward thefriction plates 43 and theseparator plates 44 and presses thefriction plates 43 and theseparator plates 44 against thebacking plate 45 fixed to theclutch drum 41. Thefriction plates 43 thus frictionally engage (fully engage or slip-engage) with theseparator plates 44 with thefriction material 70 interposed therebetween, and theclutch drum 41 is coupled to theclutch hub 42. At this time, hydraulic oil is supplied from the hydraulic control device to the canceloil chamber 49 via theoil hole 61 b, and a force that is applied to thepiston 46 by a centrifugal oil pressure generated in theengagement oil chamber 47 can be cancelled by a centrifugal oil pressure generated in the canceloil chamber 49. If the oil pressure that is supplied from the hydraulic control device to theengagement oil chamber 47 decreases, thepiston 46 is biased by the plurality of return springs 50 and is separated from thefriction plates 43. Thefriction plates 43 are thus frictionally disengaged from theseparator plates 44, and theclutch drum 41 is decoupled from theclutch hub 42. - When the clutch C1 is in an engaged state and in a disengaged state, namely when the
friction plates 43 and theseparator plates 44 are in an engaged state and in a disengaged state, hydraulic oil from the lubricating system of the hydraulic control device flows to the inside of the clutch hub 42 (the space between theclutch hub 42 and the cancel plate 48) via the oil holes 61 c of the drum-side coupling member 61 due to a centrifugal force. The hydraulic oil that has flowed to the inside of theclutch hub 42 is supplied throughout the spaces between eachfriction plate 43 and eachseparator plate 44 via the plurality ofsupply holes 421 o formed in thehub portion 421 of theclutch hub 42. Thefriction plates 43 and theseparator plates 44 in the engaged state (especially in a slip-engaged state) are thus lubricated and cooled. - As shown by thick solid arrows in
FIG. 4 , the hydraulic oil supplied throughout the spaces between eachfriction plate 43 and eachseparator plate 44 flows into eachoil groove 72 formed between thesegments 71 of eachfriction material 70 and is discharged to the outside of thedrum portion 411 via the discharge holes 411 o formed in thedrum portion 411. As described above, each of the plurality ofoil grooves 72 is formed next to itsadjacent discharge hole 411 o in the radial direction as viewed in the axial direction. The hydraulic oil can thus be smoothly guided from eachoil groove 72 to thegroove 411 a (thedischarge hole 411 o adjacent to the oil groove 72) of thesplines 411 s of thedrum portion 411 in which theexternal tooth 43 s adjacent to theoil groove 72 is fitted, and can be satisfactorily discharged to the outside of thedrum portion 411 through eachdischarge hole 411 o. Since the plurality of discharge holes 411 o are formed in thedrum portion 411 so as to overlap eachfriction plate 43 as viewed in the radial direction, the hydraulic oil can be more smoothly guided from eachoil groove 72 to itsadjacent discharge hole 411 o and can be more satisfactorily discharged to the outside of thedrum portion 411 through eachdischarge hole 411 o. - As described above, the opening 72 o on the inner peripheral side of each
oil groove 72 is formed so as to narrow as closer to the outer peripheral side. This can increase the flow velocity of the hydraulic oil that has flowed into the opening 72 o on the inner peripheral side of eachoil groove 72. As a result, the hydraulic oil can flow straighter in eachoil groove 72, and the hydraulic oil can be more satisfactorily discharged to the outside of thedrum portion 411 through theoil grooves 72 and the discharge holes 411 o adjacent to theoil grooves 72. - As the capability of discharging hydraulic oil supplied throughout the spaces between each
friction plate 43 and eachseparator plate 44 to the outside of thedrum portion 411 is thus increased, the hydraulic oil can be more satisfactorily controlled not to stay inside thedrum portion 411. This can more satisfactorily suppress generation of drag torque due to viscous shear resistance of hydraulic oil that is present between eachfriction plate 43 and eachseparator plate 44 when thefriction plates 43 and theseparator plates 44 are in a disengaged state. Since hydraulic oil is distributed more smoothly, the capability of cooling thefriction plates 43 and theseparator plates 44 when thefriction plates 43 and theseparator plates 44 are in an engaged state can also be improved. Moreover, since hydraulic oil is controlled not to stay inside thedrum portion 411, peeling, chipping, etc. of thefriction materials 70 bonded to thefriction plates 43 due to the impact with the hydraulic oil can be satisfactorily suppressed. - As described above, in this clutch C1, the
annular friction plates 43 each having thefriction material 70 attached to its surfaces are fitted in the inner periphery of thecylindrical drum portion 411 of theclutch drum 41, and theannular separator plates 44 capable of frictionally engaging with thefriction plates 43 are fitted on the outer periphery of thecylindrical hub portion 421 of theclutch hub 42. Thedrum portion 411 has thesplines 411 s on which the plurality ofexternal teeth 43 s of thefriction plates 43 are fitted, and the plurality of discharge holes (through holes) 411 o formed in thegrooves 411 a of thesplines 411 s. Moreover, eachfriction plate 43 has the plurality ofoil grooves 72 formed at intervals in the circumferential direction of thefriction plate 43 and extending in the radial direction of thefriction plate 43. The plurality ofoil grooves 72 are thus formed in eachfriction plate 43 having thefriction materials 70 attached thereto. This can more satisfactorily suppress peeling, chipping, etc. of thefriction materials 70 when thefriction plates 43 frictionally engage with theseparator plates 44 with thefriction material 70 interposed therebetween, as compared to the case where the plurality ofoil grooves 72 are formed in theseparator plates 44. Each of the plurality ofoil grooves 72 is formed next to its adjacentexternal tooth 43 s in the radial direction as viewed in the axial direction of thefriction plates 43. Hydraulic oil as a lubricating/cooling medium that is supplied throughout the spaces between thefriction material 70 of eachfriction plate 43 and eachseparator plate 44 can thus be smoothly guided from eachoil groove 72 to thegroove 411 a (thedischarge hole 411 o adjacent to the oil groove 72) of thesplines 411 s of thedrum portion 411 in which theexternal tooth 43 s adjacent to theoil groove 72 is fitted, can be satisfactorily discharged to the outside of thedrum portion 411 through eachdischarge hole 411 o, and can be more satisfactorily controlled not to stay inside thedrum portion 411. This can more satisfactorily suppress generation of drag torque due to viscous shear resistance of hydraulic oil that is present between eachfriction plate 43 and eachseparator plate 44 when thefriction plates 43 and theseparator plates 44 are in a disengaged state. In this clutch C1, thefriction materials 70 bonded to thefriction plates 43 can be more satisfactorily protected, and drag torque that is generated when the clutch C1 is in a disengaged state can further be reduced. - Each of the plurality of
oil grooves 72 is formed next to itsadjacent discharge hole 411 o in the radial direction as viewed in the axial direction of thefriction plates 43, and the plurality of discharge holes 411 o are formed in thedrum portion 411 so as to overlap thefriction plates 43 in the axial direction as viewed in the radial direction. Hydraulic oil can thus be more smoothly guided from eachoil groove 72 of eachfriction plate 43 to itsadjacent discharge hole 411 o, and can be more satisfactorily discharged to the outside of thedrum portion 411 through eachdischarge hole 411 o. The plurality of discharge holes 411 o may be formed at the positions offset in the axial direction from thefriction plates 43 as viewed in the radial direction. - Moreover, the
drum portion 411 has thesplines 411 s formed in the inner periphery thereof, and the plurality of discharge holes 411 o are formed such that the outside of thedrum portion 411 communicates with thegrooves 411 a of thesplines 411 s. Eachfriction plate 43 has the plurality ofexternal teeth 43 s that are fitted in thegrooves 411 a of thesplines 411 s, and each of the plurality ofoil grooves 72 is formed radially inward of its adjacentexternal tooth 43 s. Accordingly, by fitting theexternal teeth 43 s of eachfriction plate 43 which are located radially outward of theoil grooves 72 in thegrooves 411 a of thesplines 411 s of thedrum portion 411 which communicate with the discharge holes 411 o, eachoil groove 72 can be located next to itsadjacent discharge hole 411 o in the radial direction as viewed in the axial direction. - The openings 72 o of the plurality of
oil grooves 72 which are located on the inner peripheral side of eachfriction plate 43 are formed so as to narrow as closer to the outer peripheral side of thefriction plate 43. This can increase the flow velocity of hydraulic oil flowing in theoil grooves 72. The hydraulic oil can thus flow straighter in eachoil groove 72, and the hydraulic oil can be more satisfactorily discharged to the outside of thedrum portion 411 through theoil grooves 72 and the discharge holes 411 o adjacent to theoil grooves 72. Instead of only the openings 72 o, theentire oil grooves 72 may be formed so as to narrow from the inner peripheral side as closer to the outer peripheral side. The hydraulic oil can thus flow much straighter in eachoil groove 72. -
FIG. 5 is a sectional view showing a clutch C1B as a friction engagement element according to another embodiment. The clutch C1B includes, instead of thefriction materials 70 of the clutch C1,friction materials 70B each havingsegments 71B wider than thesegments 71 of thefriction materials 70. Eachfriction material 70B has a plurality ofnon-through grooves 73 that are formed in eachsegment 71B such that thenon-through grooves 73 are located between theoil grooves 72 adjoining each other and that are open on the inner peripheral side of thefriction plate 43. Thenon-through grooves 73 may be formed by cutting out a part on the inner peripheral side of eachsegment 71 or may be formed by pressing eachsegment 71. - When hydraulic oil flows into the
non-through grooves 73 of thefriction materials 70, eachfriction plate 43 and eachseparator plate 44 are subjected to a force in such a direction that thefriction plate 43 and theseparator plate 44 are separated from each other due to the oil pressure generated in thenon-through grooves 73. Clearance between eachfriction plate 43 and eachseparator plate 44 can thus be more properly maintained, which can further reduce drag torque that is generated between eachfriction plate 43 and eachseparator plate 44. Each of the plurality ofnon-through grooves 73 is formed next to its adjacentexternal tooth 43 s and itsadjacent discharge hole 411 o in the radial direction as viewed in the axial direction. As shown by thick dashed arrows inFIG. 6 , hydraulic oil having flowed into thenon-through grooves 73 and thus having a reduced flow velocity can thus be satisfactorily discharged to the outside of thedrum portion 411 through the discharge holes 411 o. The shape and position of thenon-through groove 73 of eachsegment 71 are not limited to those shown inFIG. 5 . For example, a plurality ofnon-through grooves 73 may be formed in eachsegment 71. In this case, not everynon-through groove 73 need necessarily be formed next to itsadjacent discharge hole 411 o in the radial direction as viewed in the axial direction. -
FIG. 6 is a sectional view showing a clutch C1C as a friction engagement element according to a still another embodiment. The clutch C1C includesfriction materials 70C instead of thefriction materials 70 of the clutch C1. Like thefriction materials 70, eachfriction material 70C is divided into a plurality ofsegments 71C. In the clutch C1C, a plurality ofoil grooves 72C each formed between thesegments 71C are formed such that a part of eachoil groove 72C which is located on the outer peripheral side of the opening 72 o widens as closer to the outer peripheral side.Such oil grooves 72C can be easily formed by cutting out a part on the outer peripheral side of eachsegment 71C. - When the rotational speed of the
friction plates 43 is relatively low, hydraulic oil is subjected to a smaller centrifugal force as compared to case where the rotational speed of thefriction plates 43 is relatively high. Accordingly, the hydraulic oil more tends to flow on eachfriction plate 43 in the opposite direction (see thick solid arrows inFIG. 6 ) to the rotation direction of the friction plate 43 (see a thin dashed arrow inFIG. 6 ) due to an inertial force. Accordingly, forming theoil grooves 72C such that a part of eachoil groove 72C which is located on the outer peripheral side of the opening 72 o widens as closer to the outer peripheral side allows hydraulic oil to flow along theoil grooves 72C when the rotational speed of thefriction plates 43 is relatively low. That is, when thefriction plates 43 and theseparator plates 44 are in a disengaged state, hydraulic oil can be satisfactorily controlled not to flow over theoil grooves 72C and thus not to be present between thefriction material 70C and theseparator plate 44 when the hydraulic oil flows in the opposite direction to the rotation direction of thefriction plates 43. This can more satisfactorily suppress generation of drag torque between eachfriction plate 43 and eachseparator plate 44. As shown by the thick dashed arrows inFIG. 6 , hydraulic oil that has flowed along eachoil groove 72C to the outer peripheral side is discharged to the outside of thedrum portion 411 thorough the discharge holes 411 o of thedrum portion 411. Eachoil groove 72C may be formed such that theentire oil groove 72C including the opening 72 o widens from the inner peripheral side as closer to the outer peripheral side, or may be formed such that theentire oil groove 72C including the opening 72 o is tilted in one direction (the opposite direction to the primary rotation direction of the friction plates 43) from the inner peripheral side as closer to the outer peripheral side. - In the above embodiment, the present disclosure is applied to the clutches C1, C1B, and C1C as wet multi-plate friction hydraulic clutches capable of connecting and disconnecting the
planetary carrier 34 of the firstplanetary gear mechanism 30 and the first sun gear 36 a of the secondplanetary gear mechanism 35 in theautomatic transmission 25. However, the present disclosure may be applied to any clutch or brake as long as it is a wet friction engagement element including a drum having a cylindrical drum portion, a hub having a cylindrical hub portion, an annular friction plate fitted in the inner periphery of the drum portion and having a friction material bonded to its surface, and an annular separator plate fitted on the outer periphery of the hub portion and capable of frictionally engaging with the friction plate. Thefriction materials segments oil grooves oil grooves adjacent discharge hole 411 o of thedrum portion 411 in the radial direction as viewed in the axial direction. - Correspondence between the main elements of the above embodiments and the main elements of the disclosure described in “SUMMARY” will be described. In the above embodiments, the
clutch drum 41 having thecylindrical drum portion 411 corresponds to the “drum,” theclutch hub 42 having thecylindrical hub portion 421 corresponds to the “hub,” theannular friction plate 43 fitted in the inner periphery of thedrum portion 411 and having thefriction materials 70 bonded to its surfaces corresponds to the “friction plate,” theannular separator plate 44 fitted on the outer periphery of thehub portion 421 and capable of frictionally engaging with thefriction plate 43 corresponds to the “separator plate,” the clutch C1 as a wet multi-plate friction hydraulic clutch corresponds to the “friction engagement element,” and the plurality of discharge holes 411 o formed at intervals in the circumferential direction of the drum portion correspond to the “plurality of through holes,” and the plurality ofoil grooves 72 formed at intervals in the circumferential direction of thefriction plate 43 and extending in the radial direction of thefriction plate 43 correspond to the “plurality of oil grooves.” - Although the embodiments of the present disclosure are described above, it should be understood that the present disclosure is not limited in any way to the above embodiments, and various modifications can be made without departing from the spirit and scope of the present disclosure. The above modes for carrying out the disclosure are merely shown as specific forms of the disclosure described in “SUMMARY” and are not intended to limit the elements of the disclosure described in “SUMMARY.”
- The present disclosure is applicable to manufacturing industries of friction engagement elements, automatic transmissions including the same, etc.
Claims (16)
1. A wet friction engagement element comprising:
a drum having a cylindrical drum portion;
a hub having a cylindrical hub portion;
an annular friction plate fitted in an inner periphery of the drum portion and having a friction material bonded to its surface; and
an annular separator plate fitted on an outer periphery of the hub portion and capable of frictionally engaging with the friction plate, wherein
the drum portion has splines on which a plurality of external teeth formed in the friction plate are fitted, and a plurality of through holes formed in grooves of the splines,
the friction plate has a plurality of oil grooves formed at intervals in a circumferential direction of the friction plate and extending in a radial direction of the friction plate, and
each of the plurality of oil grooves is located next to its adjacent one of the external teeth in the radial direction as viewed in an axial direction of the friction plate.
2. The friction engagement element according to claim 1 , wherein
each of the plurality of oil grooves is located next to its adjacent one of the through holes in the radial direction as viewed in the axial direction of the friction plate, and
the plurality of through holes are formed in the drum portion so as to overlap the friction plate as viewed in the radial direction.
3. The friction engagement element according to claim 2 , wherein
the drum portion has the splines formed in the inner periphery,
the plurality of through holes are formed such that outside of the drum portion communicates with the grooves of the splines,
the friction plate has the plurality of external teeth that are fitted in the grooves of the splines, and
each of the plurality of oil grooves is formed radially inward of its adjacent one of the external teeth.
4. The friction engagement element according to claim 3 , wherein
an opening of each of the oil grooves which is located on an inner peripheral side of the friction plate is formed so as to narrow as closer to an outer peripheral side of the friction plate.
5. The friction engagement element according to claim 4 , wherein
the friction material has a plurality of non-through grooves each formed between the oil grooves adjoining each other and each opening on the inner peripheral side of the friction plate, and
each of the plurality of non-through grooves is formed next to its adjacent one of the through holes in the radial direction as viewed in the axial direction.
6. The friction engagement element according to claim 3 , wherein
the friction material has a plurality of non-through grooves each formed between the oil grooves adjoining each other and each opening on the inner peripheral side of the friction plate, and
each of the plurality of non-through grooves is formed next to its adjacent one of the through holes in the radial direction as viewed in the axial direction.
7. The friction engagement element according to claim 2 , wherein
an opening of each of the oil grooves which is located on an inner peripheral side of the friction plate is formed so as to narrow as closer to an outer peripheral side of the friction plate.
8. The friction engagement element according to claim 7 , wherein
the friction material has a plurality of non-through grooves each formed between the oil grooves adjoining each other and each opening on the inner peripheral side of the friction plate, and
each of the plurality of non-through grooves is formed next to its adjacent one of the through holes in the radial direction as viewed in the axial direction.
9. The friction engagement element according to claim 2 , wherein
the friction material has a plurality of non-through grooves each formed between the oil grooves adjoining each other and each opening on the inner peripheral side of the friction plate, and
each of the plurality of non-through grooves is formed next to its adjacent one of the through holes in the radial direction as viewed in the axial direction.
10. The friction engagement element according to claim 1 , wherein
the drum portion has the splines formed in the inner periphery,
the plurality of through holes are formed such that outside of the drum portion communicates with the grooves of the splines,
the friction plate has the plurality of external teeth that are fitted in the grooves of the splines, and
each of the plurality of oil grooves is formed radially inward of its adjacent one of the external teeth.
11. The friction engagement element according to claim 10 , wherein
an opening of each of the oil grooves which is located on an inner peripheral side of the friction plate is formed so as to narrow as closer to an outer peripheral side of the friction plate.
12. The friction engagement element according to claim 11 , wherein
the friction material has a plurality of non-through grooves each formed between the oil grooves adjoining each other and each opening on the inner peripheral side of the friction plate, and
each of the plurality of non-through grooves is formed next to its adjacent one of the through holes in the radial direction as viewed in the axial direction.
13. The friction engagement element according to claim 10 , wherein
the friction material has a plurality of non-through grooves each formed between the oil grooves adjoining each other and each opening on the inner peripheral side of the friction plate, and
each of the plurality of non-through grooves is formed next to its adjacent one of the through holes in the radial direction as viewed in the axial direction.
14. The friction engagement element according to claim 1 , wherein
an opening of each of the oil grooves which is located on an inner peripheral side of the friction plate is formed so as to narrow as closer to an outer peripheral side of the friction plate.
15. The friction engagement element according to claim 14 , wherein
the friction material has a plurality of non-through grooves each formed between the oil grooves adjoining each other and each opening on the inner peripheral side of the friction plate, and
each of the plurality of non-through grooves is formed next to its adjacent one of the through holes in the radial direction as viewed in the axial direction.
16. The friction engagement element according to claim 1 , wherein
the friction material has a plurality of non-through grooves each formed between the oil grooves adjoining each other and each opening on the inner peripheral side of the friction plate, and
each of the plurality of non-through grooves is formed next to its adjacent one of the through holes in the radial direction as viewed in the axial direction.
Applications Claiming Priority (3)
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JP2013-203262 | 2013-09-30 | ||
JP2013203262A JP6135431B2 (en) | 2013-09-30 | 2013-09-30 | Friction engagement element |
PCT/JP2014/075858 WO2015046503A1 (en) | 2013-09-30 | 2014-09-29 | Frictional engagement element |
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US20160215830A1 true US20160215830A1 (en) | 2016-07-28 |
US10138949B2 US10138949B2 (en) | 2018-11-27 |
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Cited By (8)
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US20180058511A1 (en) * | 2015-03-31 | 2018-03-01 | Aisin Aw Co., Ltd. | Speed change device |
WO2018171994A1 (en) * | 2017-03-21 | 2018-09-27 | Zf Friedrichshafen Ag | Coupling arrangement for the drive train of a vehicle |
US10337566B2 (en) | 2016-01-19 | 2019-07-02 | Tubeworks, Inc. | Low loss direct point wet clutch fluid wall system |
CN110035916A (en) * | 2016-12-09 | 2019-07-19 | 戴姆勒股份公司 | Hybrid power head for automobile |
WO2019183590A1 (en) | 2018-03-22 | 2019-09-26 | A & A International, Llc | Hydraulic clutches, gearboxes, transmissions, energy recovery systems, mechanical one way clutches, mechanical diodes, and variable friction clutches |
WO2021108596A1 (en) * | 2019-11-26 | 2021-06-03 | A & A International, Llc | System and method for hydraulic transformer clutches |
US11441617B2 (en) | 2016-12-21 | 2022-09-13 | A & A International, Llc | Hydraulic clutches, gearboxes, transmissions, and energy recovery systems |
US11448268B2 (en) | 2018-08-03 | 2022-09-20 | A & A International, Llc | System and method for hydraulic transformer clutches |
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JP6752058B2 (en) * | 2016-06-01 | 2020-09-09 | 株式会社ダイナックス | Friction plate |
JP7021890B2 (en) * | 2017-09-27 | 2022-02-17 | 株式会社Subaru | transmission |
DE102021112393A1 (en) * | 2020-11-27 | 2022-06-02 | Schaeffler Technologies AG & Co. KG | Wet multi-plate clutch |
JP2022181340A (en) | 2021-05-26 | 2022-12-08 | マツダ株式会社 | Friction fastening device and its forming method |
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US4585096A (en) * | 1984-08-03 | 1986-04-29 | The B. F. Goodrich Company | Brake apparatus |
US5094331A (en) | 1988-03-18 | 1992-03-10 | Honda Giken Kogyo Kabushiki Kaisha | Wet-type multiplate clutch |
JPH01140028U (en) * | 1988-03-18 | 1989-09-25 | ||
US5188374A (en) * | 1992-06-01 | 1993-02-23 | General Motors Corporation | One-piece seal for rotating annular interface |
US5577582A (en) * | 1995-04-20 | 1996-11-26 | Tesma International Inc. | Polygonal clutch assembly |
JP2884483B2 (en) * | 1995-08-29 | 1999-04-19 | 本田技研工業株式会社 | Lubrication structure of wet multi-plate clutch |
JP2000145819A (en) | 1998-11-06 | 2000-05-26 | Nsk Warner Kk | Wet multiplated clutch |
JP2002081463A (en) * | 2000-09-08 | 2002-03-22 | Honda Motor Co Ltd | Wet friction plate |
JP2002106597A (en) | 2000-09-29 | 2002-04-10 | Jatco Transtechnology Ltd | Multiple wet clutch |
US6725989B1 (en) * | 2002-04-24 | 2004-04-27 | Torque-Traction Technologies, Inc. | Variably controlled torque coupling device for on-demand all-wheel drive drivetrains |
US20040099371A1 (en) | 2002-11-22 | 2004-05-27 | Hardies Tom C. | Multi-segmented friction plate with maximized steel-to-oil surface area for improved thermal capacity |
DE102006031035A1 (en) * | 2006-07-05 | 2008-01-10 | Zf Friedrichshafen Ag | Friction disc for a wet-running clutch for a vehicle |
JP2011213190A (en) * | 2010-03-31 | 2011-10-27 | Aisin Aw Co Ltd | Hybrid drive device |
-
2013
- 2013-09-30 JP JP2013203262A patent/JP6135431B2/en not_active Expired - Fee Related
-
2014
- 2014-09-29 WO PCT/JP2014/075858 patent/WO2015046503A1/en active Application Filing
- 2014-09-29 US US14/917,490 patent/US10138949B2/en active Active
Cited By (10)
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US20180058511A1 (en) * | 2015-03-31 | 2018-03-01 | Aisin Aw Co., Ltd. | Speed change device |
US10663011B2 (en) * | 2015-03-31 | 2020-05-26 | Aisin Aw Co., Ltd. | Speed change device |
US10337566B2 (en) | 2016-01-19 | 2019-07-02 | Tubeworks, Inc. | Low loss direct point wet clutch fluid wall system |
CN110035916A (en) * | 2016-12-09 | 2019-07-19 | 戴姆勒股份公司 | Hybrid power head for automobile |
US11441617B2 (en) | 2016-12-21 | 2022-09-13 | A & A International, Llc | Hydraulic clutches, gearboxes, transmissions, and energy recovery systems |
WO2018171994A1 (en) * | 2017-03-21 | 2018-09-27 | Zf Friedrichshafen Ag | Coupling arrangement for the drive train of a vehicle |
WO2019183590A1 (en) | 2018-03-22 | 2019-09-26 | A & A International, Llc | Hydraulic clutches, gearboxes, transmissions, energy recovery systems, mechanical one way clutches, mechanical diodes, and variable friction clutches |
EP3768984A4 (en) * | 2018-03-22 | 2022-01-05 | A&A International, LLC | Hydraulic clutches, gearboxes, transmissions, energy recovery systems, mechanical one way clutches, mechanical diodes, and variable friction clutches |
US11448268B2 (en) | 2018-08-03 | 2022-09-20 | A & A International, Llc | System and method for hydraulic transformer clutches |
WO2021108596A1 (en) * | 2019-11-26 | 2021-06-03 | A & A International, Llc | System and method for hydraulic transformer clutches |
Also Published As
Publication number | Publication date |
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JP2015068416A (en) | 2015-04-13 |
US10138949B2 (en) | 2018-11-27 |
JP6135431B2 (en) | 2017-05-31 |
WO2015046503A1 (en) | 2015-04-02 |
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